In recent years the importance of lithium ion batteries, nickel hydride batteries, and other secondary batteries as onboard power sources for vehicles and power sources for personal computers and portable terminals has increased. In particular, lightweight lithium ion batteries that make it possible to obtain a high energy density are expected to be advantageously used as high-output batteries for vehicles. In a typical configuration of a lithium ion battery, charging and discharging is performed by lithium ions traveling between a positive electrode and a negative electrode. The conventional technology relating to secondary batteries of this kind is described for example in Patent Documents 1 to 4.
Patent Document 1: WO 2005/067080
Patent Document 2: Japanese Patent Application Publication No. 2004-07149
Patent Document 3: Japanese Patent Application Publication No. 04-342954
Patent Document 4: WO 2005/067079
In the applications of lithium ion batteries, they are sometimes assumed to be used in a high-rate charge/discharge cycling mode (high-speed charging and discharging). A lithium ion battery that is to be used as a power source of a vehicle (for example, a lithium ion battery installed on a hybrid vehicle that is used together with another power source of a different operation principle, as in a combination of a lithium ion battery and an internal combustion engine) is a typical example of lithium ion batteries for which such usage mode is assumed. However, although typical conventional lithium ion batteries demonstrate comparatively high endurance in high-rate charge/discharge cycles, a charge/discharge pattern in which high-rate charging and discharging is repeated is known to cause easily performance deterioration (decrease in battery capacity and the like).